MGL Avionics User Forum

I have a Sonex that's a rattle can. It doesn't vibrate all that bad but it doesn't seem to matter where I've placed the SP6 it just tumbles and freaks out the whole flight and is unusable.

I mounted it on the floor board encased in foam. No luck.

Mounted on instrument panel with rubber standoff, no luck.

Im thinking about moving it further back into the tail, but i was wondering if anyone has a solution for good vibration isolation? I'm thinking mounting it in the bagge compartment on the CG with a rubber mat vibration damper would work? Or maybe 3D Printing a TPU mount?

I'd appreciate the help.

Usually the issue is too much vibration damping or mounting on a surface that moves a lot relative to the airframe path through space.

The first happens with a mounting that is too soft - the AHRS (SP-7 BTW, not SP-6) - the box moves rapidly (even if only a little) relative to the airframe.
The other related issue is mounting onto a surface that moves - have seen quite a lot of that over the years - SP-7 mounted on the actual aircraft skin (both metal as well as composite). That's pretty bad - it tends to beat like a drum from airflow and prop wash.

Best is still self adhesive velcro strips (dampens high frequency vibrations nicely) mounted onto a solid airframe member like a wing spar box.

As a test, with engine running, place you hand on the place you want to mount - if you can feel anything - so can the SP-7.
Move through the RPM range as you can get nasty resonances.

I had one aircraft where the AHRS was mounted on a shelf. Very nicely made. Looked really sturdy. As professional as you can get it. But during certain manouvers the AHRS performed really bad - and in those days it was our SP-5 AHRS which used really nice and expensive gyros from BAE systems.
The problem was as the aircraft would enter a descending bank with reduced throttle the entire shelf would start shaking badly...

BTW, just wondering - if you are really moving the SP-6 around - that's your compass. Nothing to do with the AHRS...